Expression, purification, crystallization and preliminary X-ray diffraction studies of the cmcI component of Streptomyces clavuligerus 7alpha-cephem-methoxylase.

Cephamycins are broad-spectrum beta-lactam antibiotics that show resistance to certain forms of beta-lactamases. They differ from cephalosporins by the presence of a methoxyl group at the C-7alpha position. The gene products of cmcI and cmcJ are believed to control 7alpha-methoxylation of cephalosporins through successive steps of hydroxylation and methylation. Here, the expression, purification, crystallization and initial data-collection statistics of the 236-amino-acid protein product of cmcI from Streptomyces clavuligerus is reported. The crystals belong to space group P2(1), with unit-cell parameters a = 93.6, b = 182.6, c = 103.2 A, beta = 91.05 degrees. Diffraction data were collected to 2.5 A.